Land-surface subsidence resulting from ground-water withdrawals in the Houston-Galveston region, Texas, through 1987

The ground-water system in the Houston-Galveston region, Texas is composed of layers of sand and compressible clay. The system has been divided into two major aquifers, the Chicot and Evangeline, and the underlying Burkeville confining unit. The Chicot aquifer overlies the Evangeline aquifer. The Chicot aquifer contains the most permeable sand layers and also the more compressible clay layers.